Variable-arc fin condenser



June 4, 1929. H. J. WILLHAGEN VARIABLE ARC FIN CONDENSER Filed June 2, 1925 2 Sheets-Sheet l INVENTOR June 4, 1929. H. J. WILLHAGEN VARIABLE ARC FIN CONDENSER Filed June 2, 1925 2 Sheets-Sheet 2 ORN EY Patented June 4, 1929.

. UNITED ST ES 11mm 3'. WELHA GEN, OF DETROIT, MICHIGAN.

VARIABLE-ABC rm connmwsnn.

' Appllcatlon'fled'l'une 8,

The object of my invention is to roduce a radio condenser that canbe manu actured from cast metal parts, and assembled by inserting one casting within another, and in 5 such a we that the capacity mayl be varied as desired y a rotation of one of t e castings.

Another object is to produce a variable condenser for a radio receiving set, that the two so arated sections may be each cast in a single so id piece, thus greatly reducing the manufacturin cost of the instrument.

A furt er object is to roduce a circular arc fin condenser which wi l'practicall prevent any dust particles from settlingtierein, as

it is well known that the presence of dust greatly decreases and destroys the capacity of the instrument.

' A still further object is to produce a variable condenser-havin all of its projecting fin plates formed of a single solid piece casting, to eliminate poor contact and avoid any readjustment of the plates after assembling which frequently cause a short in the instrument, and to provide a condenser that is simple in construction, but eifective in its op-' eratlon and can be manufactured at a very low cost.

I These several objects are attained in their preferred form by the construction and arrangement of parts more fully hereinafter set forth.

Similar. parts on all drawings are marked by similar numerals.

Fig. 1, is a plan view of a double quadrant condenser, each section comprising a quarter of a circle, having the alternate quadrants vacant.

Fig. 2, is a sectional view --AA of Fig. 1, showing the general construction of the 40 condenser, and the alternate interweaving of projecting arc fins of the rotor and the stator castings.

- Fig. 3, is a sectional view of the stator castll'l l %i .4, is a sectional view of the rotor casting s owing the construction of the fin memers.

Fig. 5, is a front view BB- of Fig. 3, showing the concentric circular arc fin membars, and their relative position on the segment castings. 7 i

Fig. 6, shows an alternate design of the instrument where the rotor and stator sections are made in a full half circle instead of two separated quadrant sections.

- ing the circular fin plates and the insulating 1825. Serial 1T0. 84,847.

Fig. 7, is a side view of Fig. 6, showing the stator section in a partially o enedposition. Fig. 8, is a sectional view 0 the stator section taken on the line CC of Fig. 6, show- ;neans separating samejfrom the rotor sec- 1on.' Fig. 9, is also a sectional view correspondmg to Fig. 8-, but ofthe rotor section of the device.

Fig. 10, is a front view of the stator section as seen from the section line -DD on Fi 8.

I will now describe more full the detailed construct-ion of my device, re erring to the drawings and the marks thereon.

It is known that there are variable plate condensers-for radio-use on the market at the present time, but which are formed of a series of separated flat plates mounted with interposed separators between them, and positionedito pass between a corresponding set of like plates. V

The general construction of my variable condenser com rises two circular, segment, fin castings, bot mounted on a common shaft passing throu h the center of the castings, and is provided with insulating bearings thereon for eompletel insulating each segment castin" from t 1e other. Each casting is provided with circular fin plates projecting therefrom, and so positioned on each castingas to alternatel overlap and interleave with the circular im plates of the other casting, and without forming any contact therewith.

While my condensers may be made in either a doublequadrant section, as shown in Fig. 1, or in a semi-circular section, as shown in Fig. 6, I prefer to use and describe more particularly the double quadrant type, and to wlich the specifications will more specifically re er. The sector casting -1 is preferably made of aluminum casting, or turned from a solid aluminum piece, and comprises two circular quadrant sections -wand joined together at the center by a hub 2, the quadrant sections being positioned diametrically opposite to each other on the hub 2. The hub 2 is cylindrical in form, 5 and projects bothinside and outside of the cast stator plate -1, and is arranged at right angles thereto. Cast to and pro ecting from one side of the stator plate 1- are a series of concentric, circular arc fin plates 11o f extending'the full width of the sector segments of the frame-4 and positioned concentric with the axis of the center hearing shaft 3-, which passes through the center of the hub 2. The circular segment fin plates are formed to a. true circular arc, preferably slightly ta ered toward the outer edges thereof, and alFproject from the stator late -=1 at right angles thereto. While t e stator castin 1, illustrated in the drawings, shows t e use of only four plate fins, any number of circular arc platesmay be added thereto, depending upon the capacity-of condenser desired. The center hub 2. is'provided with a counter bore 5- the-rein, provided with a cylindrical shoulder 6 for receiving and retaining a fixed bearing -7 of insulating material,

such as fiber or rubber, and which bearing is sufficiently fastened with cemenaor by a pressed fit, to withstand the turning of the inclosed shaft 3 passing therethrough. The hub -2- projecting from the outside of the-frame 1- is provided with threads -8, concentric with the hub 2--, and through which the-shaft 3 and insulator bearing 7.- also pass. The hub -8 being mainly for the purpose of passing through and connectingthe stator 1- to a supporting panel 10, and fixedly attaching same thereto by means of the threaded nut -9- engaging the threaded portion of the threaded hub -8, which can be screwed firmly against the inclosed panel support. The bearin shaft is fitted snugly within the insulated bearing 7- for the purpose of preventing free movement of the shaft 3-- and attached rotor section, ex-

cept when turned by the operating dial -11 which is fixedly attached to the outer end of the shaft. To the inside end of the shaft '3' and fixedly attached'tl1ereto,'is the rotor casting -l2, also made of a metallic casting of material similar to the stator section l-, comprisin two circular quadrant sections c and (Z, also positioned on opposite sides of a central hub 13- mounted on the bearing shaft -3 and projecting therefrom and at right angles thereto. The hub -13 projecting slightly inside of the rotor frame 12, engages the end of the insulator bearing 7, for holding the rotor and stator sections apart, and completely insulating one from the other. Like the stator section, series of concentric, circular arc fin plates --14- are cast thereto and projecting therefrom, all of said circular fin p ates being formed in a true circular arc and positioned concentric with the central bearing shaft 3, and to alternately overlap and interleave with the circular fin plates 4: of the stator section 1-, yet without touching or forming any ,contact therewith. The two sections are thoroughly insulated from each other. The rotor casting 12 is fixedly attached. to the shaft .3'-

by the set screw -.15 passing through the hub 13 and engaging; the side of the shaft. At the end of the shaft 3 is attached a flexible circuit wire 16- for connecting' the rotor section 12- into a circuit. Also attached to the outer wall of the stator casting,l is a small wire connector 17- for connecting the stator in the same circuit in which the condenser is, used. The

purpose of the device being for regulatin and varying the amount of capacity require in the circuit, andits capacit is varied by the amount of surface of over apping of the are fin plates of the rotor section with the stator section, as the rotor fins are turned into both the rotor section 18-- and the stator section -l9- are formed in a half circle, instead of two separated quarter segments as illustrated in Fig. 1. The circular arc fin plates -20-- and 2l as project from the rotor and stator sections, are likewise formed and positioned as heretofore set forth, alternatel overlapping and interleaving with the circular arc fin plates of the opposite section, each section being thoroughly insulated from each other by the insulator bearing -22- firmly pressed into the stator hub -23. Thesections are provided with. the same shaft -3 and circuit connectors 'l6 and -17, as is shown in the preferred type heretofore described, and the device operates in exactl the same manner. The capacit of the con enser being the same as of the former design, but requires the turning of the bearing shaft and attached rotor section l8-, a distance twice as far. as would be required for the double quadrant sector shown in Fig. 1.

Havin fully described my variable condenser, w lat Ielaim as my invention and 'desire to secure by Letters Patent is:

1'. A circular arc fin condenser adapted for varying and changing the capacity in a radio circuit, comprising circular sectioned metal stator and rotor sections, each section'being formed with'a center hub and having a series of concentric, circular arc finplates projecting from one side thereof and from a. single piece of metal, both mounted on a common shaft, each of said circular arc fin plates be- 7 circular arc fin plates of the opposite section, but without touching or forming any contact therewith, means for insulating the rotor section from the stator section, means for turning the rotor fins through between the fins of the stator sections about the common center shaft,.means for fixedly attaching the stator section to a fixed supporting panel, and means for connecting the two sectlons into a radio circuit.

2. A circular arc fin condenser adapted for changing the capacity within a radio circuit, comprising two metal segment castings, each of said castings provided with a series of concentric circular arc segment fin plates all cast thereon as a single piece of metal, all positioned about a center bearing through the casting, said circular arc segment fin plates being positioned at right angles to the casting, and are apart of said casting, arranged to overlap and interleave between the circular arc fin projections of the opposite section, a common bearing shaft for mounting both of the castings thereon through the center hearing therein, means for thorou hly insulating the said castings from each ot er, means for fixedly attaching one of the castings to a supporting panel, means for fastening the other casting fixedly to the common shaft passing through both sections of castings, means for rotating said shaft and attached casting so that its circular arc fin projections will pass through the spaces between the circular arc fin projections ofthe opposite fixed castin and without forming any contact therewith, and means for connectin the two insulated sections into a single in uctive circuit.

3. A variable condenser adapted for regulating the capacity of a radio circuit, comprising a cylindrical metal bearing shaft, two circular segmental metal castings mounted on said bearing shaft, positioned at right angles thereto, means for insulating the two metal castings from each other, a hub for fixedly attaching one casting to a supporting panel, means for fixedly attaching the other casting to the bearing shaft which passes through both of said castings, each of said castings being formed with a series of concentric, circular arc fin projections cast thereon all as one single piece-of metal and projecting from the sides thereof and so positioned tions.

HERMAN J. WILLHAGEN. 

